A cellular analysis of the fundamental neurobehavioral questions of central programs, sensory feedback to these programs, and higher-order control of such programs can be employed to demonstrate how inidividual neurons interact in the production of a set of behavioral acts. This investigation will provide a quantitative description of the neuronal circuitry underlying discrete behavioral processes. This is being accomplished by employing the pulmonate mollusc, Helisoma, which performs complex behaviors under conditions that allow direct analysis of neural activity. With the CNS completely exposed for intracellular microelectrode recordings from its readily identifiable neurons, this animal displays the majority of acts in its behavioral repertoire in an unaltered fashion. Specific aims of this proposal are: 1) to complete a quantitative description of the central neuronal program acting as the core of the feeding behavior with specific attention to the mechanisms of burst termination, 2) to complete our description of the individual higher-order neuronal elements we have discovered which can determine whether or not the central program for feeding is flayed out, and 3) to look at those sensory inputs which impinge on such higher-order elements. We constructed testable models of the neuronal circuitry underlying the feeding behavior. Our goal is to acquire additional quantitative data on the nature of the central program underlying this behavior so that we can understand how higher-order control units can impinge upon such a central program and "make the decision" whether or not the feeding program will be displayed behaviorally. BIBLIOGRAPHIC REFERENCES: Kaneko, C.R.S. and S.B. Kater: Feeding in Helisoma trivolvis. In press, Malacologia (1976). Merickel, M., E. D. Eyman and S. B. Kater: Analysis of a network of electrically coupled neurons producing rhythmic activity in the snail Helisoma trivolvis. In press, I.E.E.E. Trans. B.M.E. (March, 1977).